1 million years: “Highest estimated time until the red supergiant star Betelgeuse explodes in a supernova. The explosion is expected to be easily visible in daylight.”

1 million years: “On the Moon, Neil Armstrong’s ‘one small step’ footprint at Tranquility Base will erode by this time, along with those left by all twelve Apollo moonwalkers, due to the accumulated effects of space weathering.”

100 million years: “Future archaeologists should be able to identify an ‘Urban Stratum’ of fossilized great coastal cities, mostly through the remains of underground infrastructure such as building foundations and utility tunnels.”

1 billion years: “Estimated lifespan of the two Voyager Golden Records, before the information stored on them is rendered unrecoverable.”

4 billion years: “Median point by which the Andromeda Galaxy will have collided with the Milky Way, which will thereafter merge to form a galaxy dubbed ‘Milkomeda’.”

7.59 billion years: The Earth and Moon are very likely destroyed by falling into the Sun, just before the Sun reaches the tip of its red giant phase and its maximum radius of 256 times the present-day value. Before the final collision, the Moon possibly spirals below Earth’s Roche limit, breaking into a ring of debris, most of which falls to the Earth’s surface.

100 billion years: “The Universe’s expansion causes all galaxies beyond the Milky Way’s Local Group to disappear beyond the cosmic light horizon, removing them from the observable universe.”

The prevailing theory of how the Americas were settled has been than human hunters followed big game across the ice-free land bridge between North America and Asia around 13,000 years ago. These are the Clovis people you may have learned about in school. But evidence is mounting that the first humans to settle the Americas came down the Pacific Coast somewhat earlier than that.

The Cedros Island sites add to a small but growing list that supports a once-heretical view of the peopling of the Americas. Whereas archaeologists once thought that the earliest arrivals wandered into the continent through a gap in the ice age glaciers covering Canada, most researchers today think the first inhabitants came by sea. In this view, maritime explorers voyaged by boat out of Beringia — the ancient land now partially submerged under the waters of the Bering Strait — about 16,000 years ago and quickly moved down the Pacific coast, reaching Chile by at least 14,500 years ago.

Part of the problem in confirming this hypothesis is that the rise in sea level that accompanied the melting of the glaciers (a 120-meter rise globally) submerged likely settlement sites, trapping archeological evidence under hundreds of feet of ocean. (via @CharlesCMann)

Dating back roughly 300,000 years, the bones indicate that mankind evolved earlier than had been known, experts say, and open a new window on our origins.

The fossils also show that early Homo sapiens had faces much like our own, although their brains differed in fundamental ways.

Until now, the oldest fossils of our species, found in Ethiopia, dated back just 195,000 years. The new fossils suggest our species evolved across Africa.

“We did not evolve from a single cradle of mankind somewhere in East Africa,” said Phillipp Gunz, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Liepzig, Germany, and a co-author of two new studies on the fossils, published in the journal Nature.

And the specimens in question were found not in East Africa, which has become synonymous with a sort of paleoanthropological Garden of Eden, but clear on the other side of the continent — and the Sahara — in Morocco. “We’re not claiming that Morocco is the cradle of modern humankind,” the lead author, Jean-Jacques Hublin, of the Max Planck Institute for Evolutionary Anthropology, said at a press conference yesterday. Rather, he added, our emergence as a species was pan-African. “There is no Garden of Eden in Africa — or if there is, it’s Africa,” Hublin said. “The Garden of Eden is the size of Africa.”

In a 1959 talk at Caltech titled There’s Plenty of Room at the Bottom, Richard Feynman outlined a new field of study in physics: nanotechnology. He argued there was much to be explored in the realm of the very small — information storage, more powerful microscopes, biological research, computing — and that that exploration would be enormously useful.

I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, “What are the strange particles?”) but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications.

If we think of this as a design problem, there is a much better solution. Instead of expanding our environment to another planet at massive cost, why wouldn’t we miniaturise ourselves so we can expand without increasing our habitat or energy requirements, but still maintain our ability to create culture and knowledge, via information exchange.

The history of information technology and the preservation of Moore’s law has been driven by exactly this phenomenon of miniaturization. So why shouldn’t the same apply to the post technological evolution of humankind as it approaches the hypothetical ‘singularity’ and the potential ability for us to be physically embodied in silicon rather than carbon form.

When humans get smaller, the world and its resources get bigger. We’d live in smaller houses, drive smaller cars that use less gas, eat less food, etc. It wouldn’t even take much to realize gains from a Honey, I Shrunk Humanity scheme: because of scaling laws, a height/weight proportional human maxing out at 3 feet tall would not use half the resources of a 6-foot human but would use somewhere between 1/4 and 1/8 of the resources, depending on whether the resource varied with volume or surface area. Six-inch-tall humans would potentially use 1728 times fewer resources.1

Galbraith also speculates about nano aliens as a possible explanation for the Fermi paradox:

Interestingly, the same rules of energy use and distance between planets and stars would apply to any extraterrestrial aliens, so one possible explanation for the Fermi paradox is that we all get smaller and less visible as we get more technologically advanced. Rather than favoring interstellar colonization with its mind boggling distances which are impossible to communicate across within the lifetimes of individuals (and therefore impossible to hold together in any meaningful way as a civilization) perhaps advanced civilizations stick to their home planets but just get more efficient to be sustainable.

Humans are explorers. Curiosity about new worlds and ideas is one of humanity’s defining traits. One of the most striking things about the Eames’ Powers of Ten video is how similar outer space and inner space look — vast distances punctuated occasionally by matter. What if, instead of using more and more energy exploring planets, stars, and galaxies across larger and larger distances (the first half of the Eames’ video), we went the other way and focused on using less energy to explore cells, molecules, and atoms across smaller and smaller distances. It wouldn’t be so much giving up human space exploration as it would be exchanging it for a very similar and more accessible exploration of the molecular and atomic realm. There is, after all, plenty of room down there.

Update: I knew the responses to this would be good. Galbraith’s idea has a name: the transcension hypothesis, formulated by the aptly named John Smart. Jason Silva explains in this video:

The transcension hypothesis proposes that a universal process of evolutionary development guides all sufficiently advanced civilizations into what may be called “inner space,” a computationally optimal domain of increasingly dense, productive, miniaturized, and efficient scales of space, time, energy, and matter, and eventually, to a black-hole-like destination. Transcension as a developmental destiny might also contribute to the solution to the Fermi paradox, the question of why we have not seen evidence of or received beacons from intelligent civilizations.

Before we get there, however, there are a few challenges we need to overcome, as Joe Hanson explains in The Small Problem With Shrinking Ourselves:

As it often seems in such matters, science follows science fiction here. In Kurt Vonnegut’s Slapstick (Amazon), the Chinese miniaturize themselves in response to the Earth’s decreasing resources.

In the meantime, Western civilization is nearing collapse as oil runs out, and the Chinese are making vast leaps forward by miniaturizing themselves and training groups of hundreds to think as one. Eventually, the miniaturization proceeds to the point that they become so small that they cause a plague among those who accidentally inhale them, ultimately destroying Western civilization beyond repair.

Through infection, conversion and assimilation of humans and other organisms the cells eventually aggregate most of the biosphere of North America into a region seven thousand kilometres wide. This civilization, which incorporates both the evolved noocytes and recently assimilated conventional humans, is eventually forced to abandon the normal plane of existence in favor of one in which thought does not require a physical substrate.

“Downsizing,” after all, starts off in Norway and takes place in a not-too-distant future where humans are now able to shrink themselves to 1/8 their size as a means to battle over-consumption and the rapid depletion of earth’s natural resources, thanks to enlightened hippie-like Scandinavian scientists. “Smalls” get small, then become members of small cities (the main characters moves to a city called Leisureland) protected by large nets (keeps the bugs out) and built like Disney’s Celebration Town (all planned, all pre-fabricated). Small people cash-in their savings and retire small; 1 big dollar equals 500 small dollars. Smalls live on less food, less land, and produce less trash. As the story progresses, Americans are free to get small, but in Europe, where resources are beginning to truly run out, legislation arises suggesting 40% of the population get shrunk (whether they like it or not). For the big, the world grows smaller and scarier; for the small, the world grows bigger and scarier.

Word is that Matt Damon will play the lead role. Mr. Payne, consider a title change to “Nano Sapiens”? (via @stephenosberg)

This is not a straightforward matter however. The 6-inch human wouldn’t eat 1728 times less food…that would mean you could live on a Big Mac for a year. Small animals often eat a significant percentage of their body weights each day, which normal-sized humans never approach. For example, according to this chart a grey squirrel weighs about 21 oz and eats about 1.6 oz of food, the equivalent of a 180-pound human eating about 14 pounds of food a day.↩

In Sapiens (which I enjoyed and recommend), Yuval Noah Harari gave us a “brief history of humankind”. In his upcoming Homo Deus, Harari turns “his focus toward humanity’s future, and our quest to upgrade humans into gods”.

Over the past century humankind has managed to do the impossible and rein in famine, plague, and war. This may seem hard to accept, but, as Harari explains in his trademark style — thorough, yet riveting — famine, plague and war have been transformed from incomprehensible and uncontrollable forces of nature into manageable challenges. For the first time ever, more people die from eating too much than from eating too little; more people die from old age than from infectious diseases; and more people commit suicide than are killed by soldiers, terrorists and criminals put together. The average American is a thousand times more likely to die from binging at McDonalds than from being blown up by Al Qaeda.

What then will replace famine, plague, and war at the top of the human agenda? As the self-made gods of planet earth, what destinies will we set ourselves, and which quests will we undertake? Homo Deus explores the projects, dreams and nightmares that will shape the twenty-first century — from overcoming death to creating artificial life. It asks the fundamental questions: Where do we go from here? And how will we protect this fragile world from our own destructive powers? This is the next stage of evolution. This is Homo Deus.

How old are different parts of our bodies? Does anything stick around the entire time? The hair on our bodies lasts only a few years. Fingernails are fully replaced every six months. Your skin lasts 2-4 weeks. Even your blood and bones regenerate every so often. There’s at least one part of your body with lasts the whole time you’re alive, which I found somewhat surprising. See the ship of Theseus paradox.

The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their places, in so much that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.

Analysis of growth rings from pine trees in Sweden shows that the proliferation of atomic tests in the 1950s and 1960s led to an explosion in levels of atmospheric carbon 14. Now, Jonas Frisen and colleagues at the Karolinska Institute in Stockholm have taken advantage of this spike in C14 to devise a method to date the birth of human cells. Because this test can be used retrospectively, unlike many of the current methods used to detect cell proliferation, and because it does not require the ingestion of a radioactive or chemical tracer, the method can be readily applied to both in vivo and postmortem samples of human tissues.

Kurzgesagt gives us a short tour of human history, from the six different species of human that existed 100,000 years ago to the present. If you found that interesting and want more detail, you should read Sapiens…Kurzgesagt used it as a major reference here.

Most books about the history of humanity pursue either a historical or a biological approach, but Dr. Yuval Noah Harari breaks the mold with this highly original book that begins about 70,000 years ago with the appearance of modern cognition. From examining the role evolving humans have played in the global ecosystem to charting the rise of empires, Sapiens integrates history and science to reconsider accepted narratives, connect past developments with contemporary concerns, and examine specific events within the context of larger ideas.

Kurzgesagt and CGPGrey collaborated on a pair of videos about the self. The first video considers the human being as a collection of cells. How many of those cells can you take away before you stop being you? And does that question even make sense? The second video notes that if you sever the connection between the two halves of the human brain, they will each seemingly continue to operate as separate entities. But which of those entities is you? Are there two yous?

In the 90s, Bruniquel Cave was discovered to have a chamber containing an interesting human-built structure made from broken stalagmites. Carbon dating of a burnt bear bone within the chamber put the age of the activity at 47,600 years ago, smack dab in the Neanderthal era in that area. But recently, after a lull in research about these cave structures, analysis of uranium levels in the broken stalagmites resulted in a much older date for the construction: 176,500 years ago.

Nor is it clear how the Neanderthals made the structures. Verheyden says it couldn’t have been one lone artisan, toiling away in the dark. Most likely, there was a team, and a technically skilled one at that. They broke rocks deliberately, and arranged them precisely. They used fire, too. More than 120 fragments have red and black streaks that aren’t found elsewhere in the chamber or the cave beyond. They were the result of deliberately applied heat, at intensities strong enough to occasionally crack the rock. “The Neanderthal group responsible for these constructions had a level of social organization that was more complex than previously thought,” the team writes.

And, there are a lot of them, fossil-wise: “Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.”

But we don’t yet know exactly how long ago they lived: maybe two million years ago, when the Homo genus emerged, or as late as a hundred thousand years ago, when it contracted to, well, us. In an accompanying article, Chris Stringer gets a little testy about it.

Frustratingly, the rich and informative H. naledi material remains undated. Given that this hominin material could conceivably even date within the last 100,000 years, I am puzzled by the apparent lack of attempts to estimate its age. This could have been achieved directly via radiocarbon dating (even if only to test whether the material lies beyond the effective range of that method) or indirectly based on ancient DNA samples. For example, after ancient DNA was successfully recovered from the Sima de los Huesos fossils, it was used to date them to about 400,000 years old (Meyer et al., 2014). Moreover, tests on even small fragments of bone and tooth enamel could have narrowed down the possible age range and at least ruled out either a very ancient or very young age (GrÃ¼n, 2006).

As Dan Cohen points out, this discovery is also unusual in that it didn’t make its splash at Science or Nature, but eLife, a free, open-access journal. Study leader Lee Berger tells Buzzfeed the article was rejected by Nature because the authors couldn’t meet the mag’s demands to squeeze the whole thing into 2500 words. Well, whatever the reason for going open-access, we of the science-following-but-not-institutional-password-having-audience approve.

Update: Ed Yong has a terrific account of the discovery, with a ripping narrative about the caving team’s expedition and an intelligent analysis of the new species and its implications. Well worth reading.

Up until very recently, humans were thought to be the only animals who made and used stone tools, an era in human development that began roughly 3.3 million years ago. But according to this piece at the BBC, some chimpanzees and monkeys in various places around the globe have been using primitive stone tools for hundreds or even thousands of years.

Boesch and his colleagues had previously studied modern chimpanzee stone tool culture in the region. This research revealed that the chimpanzees have an idiosyncratic way of choosing and using their tools.

For instance, chimpanzees will often deliberately opt for particularly large and heavy stone hammers, between 1kg and 9kg, while humans prefer to use stones that weigh 1kg or less. Many of the 4300-year-old stone tools weighed more than 1kg, suggesting they were used by chimpanzees.

Chimpanzees also use their stone tools to crack open certain types of nuts that humans don’t eat. Starch residues on some of the ancient tools came from these nuts.

Together, these findings led to an obvious conclusion: chimpanzees have been using stone tools in the rainforests of Ivory Coast for at least 4300 years.

Modern humans formed an alliance with wolves soon after we entered Europe, argues Shipman. We tamed some and the dogs we bred from them were then used to chase prey and to drive off rival carnivores, including lions and leopards, that tried to steal the meat.

“Early wolf-dogs would have tracked and harassed animals like elk and bison and would have hounded them until they tired,” said Shipman. “Then humans would have killed them with spears or bows and arrows.

“This meant the dogs did not need to approach these large cornered animals to finish them off — often the most dangerous part of a hunt — while humans didn’t have to expend energy in tracking and wearing down prey. Dogs would have done that. Then we shared the meat. It was a win-win situation.”

At that time, the European landscape was dominated by mammoths, rhinos, bison and several other large herbivores. Both Neanderthals and modern humans hunted them with spears and possibly bows and arrows. It would have been a tricky business made worse by competition from lions, leopards, hyenas, and other carnivores, including wolves.

“Even if you brought down a bison, within minutes other carnivores would have been lining up to attack you and steal your prey,” said Shipman. The answer, she argues, was the creation of the human-wolf alliance. Previously they separately hunted the same creatures, with mixed results. Once they joined forces, they dominated the food chain in prehistoric Europe — though this success came at a price for other species. First Neanderthals disappeared to be followed by lions, mammoths, hyenas and bison over the succeeding millennia. Humans and hunting dogs were, and still are, a deadly combination, says Shipman.

A shell found in the 1890s was recently found to have what scientists are calling the world’s oldest “abstract marking”, a 500,000-year-old etching made by Homo erectus, an extinct ancestor of modern humans.

Close inspection under the microscope suggested that the engraving was intentional. The weathering patterns of the grooves, each of which is about 1 centimetre long, show signs of significant ageing, and there are no gaps between turns, indicating that the maker paid attention to detail. He or she probably made the engraving on a fresh shell, and the newly made etching would have resembled white lines on a dark canvas, Joordens’ team notes. Sand grains still embedded in the shell were dated to around 500,000 years ago.

“What it begins to suggest is that we’re looking at a Lord of the Rings-type world — that there were many hominid populations,” says Mark Thomas, an evolutionary geneticist at University College London who was at the meeting but was not involved in the work.

But, more interestingly, the analysis also detected the Denisovans also bred with an as-yet-unknown species of humans.

The Denisovan genome indicates that the population got around: Reich said at the meeting that as well as interbreeding with the ancestors of Oceanians, they also bred with Neanderthals and the ancestors of modern humans in China and other parts of East Asia. Most surprisingly, Reich said, the genomes indicate that Denisovans interbred with yet another extinct population of archaic humans that lived in Asia more than 30,000 years ago — one that is neither human nor Neanderthal.

Is this the first time a new human species has been discovered through DNA evidence alone?

Trevor Paglen speculates that human civilization’s longest lasting monuments will be the satellites in geostationary orbits around the Earth.

Humanity’s longest lasting remnants are found among the stars. Over the last fifty years, hundreds of satellites have been launched into geosynchronous orbits, forming a ring of machines 36,000 kilometers from earth. Thousands of times further away than most other satellites, geostationary spacecraft remain locked as man-made moons in perpetual orbit long after their operational lifetimes. Geosynchronous spacecraft will be among civilization’s most enduring remnants, quietly circling earth until the earth is no more.

Billions of years from now, he began to narrate, long after city lights and the humans who made them have disappeared from the Earth, other intelligent species might eventually begin to see traces of humanity’s long-since erased presence on the planet.

Consider deep-sea squid, Paglen suggested, who would have billions of years to continue developing and perfecting their incredible eyesight, a sensory skill perfect for peering through the otherwise impenetrable darkness of the oceans — yet also an eyesight that could let them gaze out at the stars in deep space.

Perhaps, Paglen speculated, these future deep-sea squid with their extraordinary powers of sight honed precisely for focusing on tiny points of light in the darkness might drift up to the surface of the ocean on calm nights to look upward at the stars, viewing a scene that will have rearranged into whole new constellations since the last time humans walked the Earth.

The latest word on Homo floresiensis, the potential new species of hobbit-like humans discovered ten years ago in Indonesia, concerns a pair of papers which argue the single specimen found is actually a regular human with Down syndrome.

Now, the debate has reignited with two new papers published this week by a team of researchers from Penn State and other institutions. In one of those papers, they argue that the Flores skull is not a new species, but instead represents an ancient person with Down syndrome.

The researchers also point out, in the second paper, that the original report on the bones seemed to have exaggerated the skull’s diminutive size. Cranial measurements and features, along with shorter thigh bones, the team found, all correspond with modern manifestations of Down syndrome. “The difference is significant, and the revised figure falls in the range predicted for a modern human with Down syndrome from the same geographic region,” they say in a statement.

Researchers here say they have unearthed stone tools proving that humans reached what is now northeast Brazil as early as 22,000 years ago. Their discovery adds to the growing body of research upending a prevailing belief of 20th-century archaeology in the United States known as the Clovis model, which holds that people first arrived in the Americas from Asia about 13,000 years ago.

“If they’re right, and there’s a great possibility that they are, that will change everything we know about the settlement of the Americas,” said Walter Neves, an evolutionary anthropologist at the University of Sao Paulo whose own analysis of an 11,000-year-old skull in Brazil implies that some ancient Americans resembled aboriginal Australians more than they did Asians.

Up and down the Americas, scholars say that the peopling of lands empty of humankind may have been far more complex than long believed. The radiocarbon dating of spear points found in the 1920s near Clovis, N.M., placed the arrival of big-game hunters across the Bering Strait about 13,000 years ago, long forming the basis of when humans were believed to have arrived in the Americas.

More recently, numerous findings have challenged that narrative. In Texas, archaeologists said in 2011 that they had found projectile points showing that hunter-gatherers had reached another site, known as Buttermilk Creek, as early as 15,500 years ago. Similarly, analysis of human DNA found at an Oregon cave determined that humans were there 14,000 years ago.

This is nutty…by chance, a group of archaeologists found what are believed to be the oldest known human footprints outside of Africa on a beach in England. The footprints are an estimated 800,000 years old and are now completely gone. The tide that uncovered them washed them away in less than a month.

The footprints have been described as “one of the most important discoveries, if not the most important discovery that has been made on [Britain’s] shores,” by Dr Nick Ashton of the British Museum.

“It will rewrite our understanding of the early human occupation of Britain and indeed of Europe,” he told BBC News.

The markings were first indentified in May last year during a low tide. Rough seas had eroded the sandy beach to reveal a series of elongated hollows.

Caspari says it wasn’t a biological change that allowed people to start living reliably to their 30s and beyond. (When she looked at other populations of Neanderthals and Homo sapiens that lived in the same place and time, the two different species had similar proportions of old people, suggesting the change was not genetic.) Instead, it was culture. Something about how people were living made it possible to survive into old age, maybe the way they found or stored food or built shelters, who knows. That’s all lost-pretty much all we have of them is teeth-but once humans found a way to keep old people around, everything changed.

Old people are repositories of information, Caspari says. They know about the natural world, how to handle rare disasters, how to perform complicated skills, who is related to whom, where the food and caves and enemies are. They maintain and build intricate social networks. A lot of skills that allowed humans to take over the world take a lot of time and training to master, and they wouldn’t have been perfected or passed along without old people. “They can be great teachers,” Caspari says, “and they allow for more complex societies.” Old people made humans human.

What’s so special about age 30? That’s when you’re old enough to be a grandparent. Studies of modern hunter-gatherers and historical records suggest that when older people help take care of their grandchildren, the grandchildren are more likely to survive. The evolutionary advantages of living long enough to help raise our children’s children may be what made it biologically plausible for us to live to once unthinkably old ages today.

Did you know that there are new human beings? Like, not just new human babies but new species of humans? And not just new species of humans, but new species of humans who lived at the same time as, and even possibly bred with, modern humans, aka us? (Helloooooo, mesofacts.)

If you’ve read kottke.org over the years, you’ve likely heard of Homo floresiensis (aka Flores man, aka Hobbits), a species whose remains were discovered in present-day Indonesia in 2003. Homo floresiensis lived 95,000 to 13,000 years ago and stood about three feet high.

In this month’s National Geographic, Jamie Shreeve tells the story of the 2010 discovery of the Denisovans, hominids who lived in modern-day Russia as late as 40,000 years ago. Only a handful of bone fragments and teeth have been recovered, but DNA and other evidence suggests that Denisovans, Neanderthals, and modern humans lived together in the same place and interbred.

By the time of the Denisova symposium, Pääbo and his colleagues had published first drafts of the entire Neanderthal and Denisovan genomes. Reading so many more pages allowed Pääbo and his colleagues, including David Reich at Harvard University and Montgomery Slatkin at the University of California, Berkeley, to discover that human genomes today actually contain a small but significant amount of Neanderthal code — on average about 2.5 percent. The Neanderthals still may have been swept into extinction by the strange, high-browed new people who followed them out of Africa, but not before some commingling that left a little Neanderthal in most of us, 50,000 years later. Only one group of modern humans escaped that influence: Africans, because the commingling happened outside that continent.

Although the Denisovans’ genome showed that they were more closely related to the Neanderthals, they too had left their mark on us. But the geographic pattern of that legacy was odd. When the researchers compared the Denisovan genome with those of various modern human populations, they found no trace of it in Russia or nearby China, or anywhere else, for that matter — except in the genomes of New Guineans, other people from islands in Melanesia, and Australian Aborigines. On average their genomes are about 5 percent Denisovan. Negritos in the Philippines have as much as 2.5 percent.

The Red Deer Cave dwellers’ unusual features included a flat face, a broad nose, a jutting jaw that lacked a chin, large molar teeth, a rounded braincase with prominent brow ridges, and thick skull bones, the researchers say.

Their brains were “moderate in size,” Curnoe added.

Despite this seemingly primitive human design, radiocarbon dating of charcoal from the fossil deposits suggests the Red Deer Cave people lived just 14,500 to 11,500 years ago, the team says-a time by which all other human species, such as Neanderthals, are thought to have died out.

As with the other potential new human species, and as is proper in science, there is some skepticism about the Red Deer Cave people.

The team’s suggestion that the Red Deer Cave people are somehow evolutionarily unique is receiving a skeptical reception from other scientists.

Physical anthropologist Erik Trinkaus described the findings as “an unfortunate overinterpretation and misinterpretation of robust early modern humans, probably with affinities to modern Melanesians”-indigenous peoples of Pacific islands stretching from New Guinea to Fiji (map).

“There is nothing extraordinary” about the newly announced fossil human, added Trinkaus, of Washington University in St. Louis, via email.

In the last few years, scientists have discovered that before Neanderthals went extinct around 30,000 years ago, they interbred with modern humans. As a result, many humans alive today contain Neanderthal DNA in their genomes, typically between 1-4%.

Yesterday, a few of the editors at The Atlantic had their genes analyzed for Neanderthal DNA: Alexis Madrigal had 3.6%, Steve Clemons had 4.3%, and James Fallows had 5%. Personal genetic information company 23andMe added the ability to determine your Neanderthal DNA percentage a few months ago and it turns out 2.7% of my DNA is from Neanderthals, compared to 2.5% for the average 23andMe user.

If you have a 23andMe acct, you can check your percentage by logging in and going to “Ancestry Labs” in the sidebar.

When elephants began to die out, Homo erectus “needed to hunt many smaller, more evasive animals. Energy requirements increased, but with plant and protein intake limited, the source had to come from fat. He had to become calculated about hunting,” Ben-Dor says, noting that this change is evident in the physical appearance of modern humans, lighter than Homo erectus and with larger brains.

Archaeologists and experts on early nautical history said the discovery appeared to show that these surprisingly ancient mariners had craft sturdier and more reliable than rafts. They also must have had the cognitive ability to conceive and carry out repeated water crossing over great distances in order to establish sustainable populations producing an abundance of stone artifacts.

Internet, meet Ardi, the newest member of the human branch of the primate family tree.

Or rather, the oldest. Discovered in Ethiopia in 1994, Ardi is a 4.4 million-year-old partial skeleton of a female Ardipithecus ramidus.

The fossil puts to rest the notion, popular since Darwin’s time, that a chimpanzee-like missing link — resembling something between humans and today’s apes — would eventually be found at the root of the human family tree. Indeed, the new evidence suggests that the study of chimpanzee anatomy and behavior — long used to infer the nature of the earliest human ancestors — is largely irrelevant to understanding our beginnings.

Ardi instead shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas. As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like.

This is a major discovery; Science is devoting a special issue to the find with 11 detailed peer-review papers and general summaries. I expect we’ll be hearing more about this in the coming weeks as all that science filters through the lay media. (thx, jeff)

Other archaeologists agreed that the findings established more firmly than before the presence of people on the continent at least 1,000 years before the well-known Clovis people, previously thought to be the first Americans. Recent research at sites in Florida and Wisconsin also appears to support the earlier arrivals, and a campsite in Chile indicates migration deep into South America by 14,600 years ago.

Speaking of memes, Susan Blackmore theorizes that humans are just machines for propagating them.

Memes are using human brains as their copying machinery. So we need to understand the way human beings work.

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Up until very recently in the world of memes, humans did all the varying and selecting. We had machines that copied — photocopiers, printing presses — but only very recently do we have artificial machines that also produce the variations, for example (software that) mixes up ideas and produces an essay or neural networks that produce new music and do the selecting. There are machines that will choose which music you listen to. It’s all shifting that way because evolution by natural selection is inevitable. There’s a shift to the machines doing all of that.

When asked what the future will look like, she says, “it will look like humans are just a minor thing on this planet with masses (of) silicon-based machinery using us to drag stuff out of the ground to build more machines.”

The brisk rate of human selection occurred for two reasons, Dr. Moyzis’ team says. One was that the population started to grow, first in Africa and then in the rest of the world after the first modern humans left Africa. The larger size of the population meant that there were more mutations for natural selection to work on. The second reason for the accelerated evolution was that the expanding human populations in Africa and Eurasia were encountering climates and diseases to which they had to adapt genetically. The extra mutations in their growing populations allowed them to do so.

Dr. Moyzis said it was widely assumed that once people developed culture, they protected themselves from the environment and from the forces of natural selection. But people also had to adapt to the environments that their culture created, and the new analysis shows that evolution continued even faster than before.